Improvement in steam-engines



S t am E n g i n es;

red Jan. 6, 1874;

Pat

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FIGS.

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UNITED STATES PATENT FFICE.

EDwARD EIELD AND ERANCIs M. COTTON, OEILONDON, ENGLAND.

IMPROVEMENT IN STEM-ENGINES.`

Specicatiou forming part of Letters Patent No. 146,239, dated January 6, 1874.; application filed April 24, 1873.

To all whom 'it may concern:

Be it known that we, AEDWARD FIELD and FRANCIS MICHAEL COTTON, both of London, Kingdom of Great Britain and Ireland, have invented certain Improvements in Steam-Engines, of which the following is a specification:

This invention has reference to engines of the kind known as compound high and low pressure engines, in which high-pressure steam is made to do duty rst in a high-pressure cylinder, and thence passes into a second or lowpressure cylinder, wherein it expands and acts upon another piston, as 'well understood.'

The lirst part of our invention relates to the construction of such engines with a combined high-pressure cylinder and low-pressure piston, which Works Wholly within the low-press ure cylinder, a steam-chamber being formed between the two cylinders, whence steam is supplied alternately to the respective ends of the high-pressure cylinder, and is from then ce exhausted directly into the same ends of the lowpressure cylinder. The second part of our invention relates to the construction of the engine with valves carried by the combined high-pressure cylinder and low-pressure piston, for governing the communication between high and low pressure cylinders, and with other valves working in a separate valve-chamber outside of the low-pressure cylinder, for opening and closing its exhaustports. The third part of our invention relates to the actuating of the whole of the said valves directly by means of high-pressure steam in the respective ends of the low-pressure cylinder.

. Figure 1, Sheet l, is a longitudinal vertical section of parts of a steam-engine embodying the first, second, and third parts of our invention. Fig. 2 is a transverse section taken in the line AB of Fig. 1. Fig. 3 is a transverse section taken in the line C D of Fig. 1. Fig. 4 is a section taken in the line E F of Fig. 1. Fig. 5 is an end view of the exhaust-valvechamber cover.

We arrange a reciprocating high-pressure cylinder or chamber, a, wholly within a lowpressure cylinder or chamber, b, with their axes parallel to each other, the two cylinders being, by preference, concentric, as shown. The high-pressure cylinder a, with its ilan ges and covers, forms the piston of the low-pressure cylinder b. So itwill be understood that, whenever we mention hereafterthe low-pressure piston, we refer to the high-pressure cylinder, and vice versa. `The piston c of the highpressure cylinder a is xed, and maintains a constant position relativelyto the low-pressure cylinder b. The'annular spaced between the high and low pressure cylinders constitutes a steam-chamber, into which steam from the boiler constantly flows bythe inlet a', for suprequired, by the said valves. The high-pressure cylinder a is arranged `to communicate` with the low-pressure cylinder b at one end by the port f and valve-chamber e3, and at the other end by the port f' and valve-chamber e?. The

valve-chambers c3 e4 communicate with the annular steam-chamber d at `their inner ends,

and with the interior of the lowlpressure cyl-` y in der b at their outer ends, and, with the ports f f', form short passages or ways between the two cylinders at their respective ends, the com# munication being opened and closed, as re-` quired, by the movement of the piston-valves e el. The outer face of each ofthesevalves is wholly exposed to the action of the steamfor the time being in the corresponding end of the low-pressure cylinder b. n nl are lugs, cast on the cylinder a, bored in a line with and to the same diameter as the valve-chambers, and having their inner ends closed by means of cushionblocks "n2` at?, which blocks `are bored to allow thevalve-rod to pass' throughl them, and, in conjunction with the lugs fn. n1, form steam-cushion chambers to prevent violent shock of the valves when thrown over.

The ports h It', formed in the low-pressure cyli l inder b, and governed by the piston-valvesi il, conductl the exhaust-steam from the respective ends of the low-pressure cylinder bjinto the valve-chamber k, whence it escapes bythe exhaust k. The valves 'i il (like the valves e el) are exposed at their outer faces to the pressure, for the time being, in the corresponding ends of the low-pressure cylinder b, and are connected together by a spindle, i6, which also carries the small pistons t2 i3, operating, in conjunction with the partitions 4125, to cushion the exhaust-valves.

The operation of the engine is as follows: On starting the engine, its iirst stroke is effected by high-pressure steam entering the high-pressure cylinder a, and exerting its iniiuence between one end of that cylinder and itsixed piston c, thereby moving the combined high-pressure cylinder and low-pressure piston a toward one end of the low-pressure cylinder b. The high-pressure steam whereby this first stroke has been effected then passes directly into the same end of the low-pressure cylinder b, and a fresh supply of high-pressure steam enters the other end of the high-pressure cylinder a, so that the combined high-pressure cylinder and low-pressure piston c is caused to perform its second or return' stroke by the combinedaction of the expanding steam in the low-pressure cylinder'b and of the high-pressure steam in the high-pressure cylinder a, thus completing the rst double stroke or revolution of the engine. The subsequent strokes are effected similarly to the second or return stroke, just mentioned, by the combined action of high-pressure steam from the highpressure cylinder a expanding into the lowpressure cylinder b, and of fresh supplies of high-pressure steam admitted into the highpressure cylinder a at each stroke, as described, the expanded steam, after having done duty in the low-pressure cylinder b during each stroke, being exhausted therefrom or conveyed y to the condenser or atmosphere during the next or return stroke.

Y The drawing shows the position of the parts which obtains when the low-pressure piston a has moved nearly to the end of the low-pressure cylinder b, and has thereby first closed the exhaust-port h', and subsequently opened a communication, by the groove or channel l, between that end of the low-pressure cylinder and the steam-chamber d, thereby admitting high-pressure steam into the low-pressure cylinder, which steam has formed a cushion for the low-pressure piston a, and has thrown over the valves e e1 and the exhaust-valves t' il by acting on the faces of the valves el and 'The valves having been thus thrown over, the highpressure steam which has just done duty in the cylinder a is now passing directly, by the port j" and the valve-chamber e4, into the end b of the low-pressure cylinder b the communication between the other end of the highpressure cylinder a and the corresponding end of the low-pressure cylinder b is closed by the valve e and fresh high-pressure steam is passing from the annular steam-chamber d, by the valve-chamber e3 and port f, into the end a of the high-pressure cylinder ce for the return stroke. The port h is closed by the valve fil, and the port h is open, so that the expanded steam in the low-pressure cylinder ispassing, by the port h and valve-chamber k, to the exhaust 7c. Y Y

The tappets m m and the prolongation i7 of the valve-spindle i6 are for the purpose of moving the valves by hand, in the event of their becoming set through disuse.

Our improved compound engine may obvioiisly be made with valves differing more or less in their arrangement from those above described without departing from the distinctive character of our invention, as respects which Ve claiml. The combination of the high-pressure cylinder af, the low-pressure cylinderb, of which the cylinder a is the piston, valves arranged and operating as described, and the steamchamber d, surrounding the cylinder a and communicating with the steam-generator, as set forth.

2. The valves e cl, working in the chambers e3 e4, carried by the combined high-pressure cylinder and low-pressure piston a, in combination with the exhaust-valif'es M1, working in the. chamber k outside the low-pressure cylinder b, all arranged substantially as specified.

3. Thecombination of the cylinder b, inner sliding cylinder a, and openings provided with valves, and arranged to admit live steam to the valves at the end of each stroke, for the purpose set forth.

EDVARD FIELD. FRANCIS M. COTTON.

Vitnesses:

W. LLOYD Wisin,

Patent Agent, London. H. C. WILEs,

Loudon. 

